<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="initial-scale=1.0, user-scalable=no, width=device-width">
  <title>Color Manipulation</title>
  <link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.0/dist/css/bootstrap.min.css"
    crossorigin="anonymous">
  <link rel="stylesheet" type="text/css"
    href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@6.1.2/css/fontawesome.min.css"
    crossorigin="anonymous">
  <link rel="stylesheet" type="text/css"
    href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@6.1.2/css/solid.css" crossorigin="anonymous">
  <link rel="stylesheet" type="text/css"
    href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@6.1.2/css/brands.css" crossorigin="anonymous">
  <link rel="stylesheet" type="text/css" href="./theme/ol.css">
  <link rel="stylesheet" type="text/css" href="/theme/site.css">
  <link rel="stylesheet" type="text/css" href="color-manipulation.css">
  <link rel="icon" type="image/svg+xml" href="/theme/img/logo-light.svg" media="(prefers-color-scheme: light)" />
  <link rel="icon" type="image/svg+xml" href="/theme/img/logo-dark.svg" media="(prefers-color-scheme: dark)" />
</head>

<body>
  <header class="navbar navbar-expand-md navbar-dark mb-3 px-3 py-0 fixed-top" role="navigation">
    <a class="navbar-brand" href="/"><img src="/theme/img/logo-dark.svg" width="70" height="70"
        alt="">&nbsp;OpenLayers</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#olmenu"
      aria-controls="olmenu" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>

    <!-- menu items that get hidden below 768px width -->
    <nav class="collapse navbar-collapse" id="olmenu">
      <ul class="nav navbar-nav ms-auto">
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="docdropdown" role="button" data-bs-toggle="dropdown"
            aria-haspopup="true" aria-expanded="false">Docs</a>
          <div class="dropdown-menu dropdown-menu-end mb-3" aria-labelledby="docdropdown">
            <a class="dropdown-item" href="/doc/">Docs</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="/doc/quickstart.html"><i class="fa fa-check fa-fw me-2 fa-lg"></i>快速入门</a>
            <a class="dropdown-item" href="/doc/faq.html"><i class="fa fa-question fa-fw me-2 fa-lg"></i>常见问题</a>
            <a class="dropdown-item" href="/doc/tutorials/"><i class="fa fa-book fa-fw me-2 fa-lg"></i>教程</a>

          </div>
        </li>
        <li class="nav-item"><a class="nav-link" href="/en/latest/examples/">Examples</a></li>
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="apidropdown" role="button" data-bs-toggle="dropdown"
            aria-haspopup="true" aria-expanded="false">
            <i class="fa fa-sitemap me-1"></i>API
          </a>
          <div class="dropdown-menu dropdown-menu-end mb-3" aria-labelledby="apidropdown">
            <a class="dropdown-item" href="/en/latest/apidoc/"><i class="fa fa-sitemap fa-fw me-2 fa-lg"></i>v8.2.0
              (latest)</a </div>
        </li>
      </ul>
    </nav>
  </header>

  <div class="container-fluid line-numbers">
    <div id="latest-check" class="alert alert-warning alert-dismissible" role="alert" style="display:none">
      <button id="latest-dismiss" type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
      This example uses OpenLayers v<span>8.2.0</span>. The <a id="latest-link" href="#" class="alert-link">latest</a>
      is v<span id="latest-version"></span>.
    </div>


    <div class="row-fluid">
      <a href="#" id="codepen-button" class="btn btn-link float-end">
        <i class="fab fa-codepen fa-lg"></i> Edit
      </a>
      <div class="span12">
        <h4 id="title">Color Manipulation</h4>
        <p class="tags">
          <span class="badge-group">
            <a href="./index.html?q=color" class="badge badge-info">color</a><a
              class="badge badge-info tag-modal-toggle" data-bs-toggle="modal" data-bs-target="#tag-example-list"
              data-title="color" data-content="&lt;ul class=&quot;list-group&quot;&gt;
                  &lt;li&gt;&lt;a class=&quot;list-group-item list-group-item-action active&quot; href=&quot;./color-manipulation.html&quot;&gt;Color Manipulation&lt;/a&gt;
                  &lt;/ul&gt;" tabindex="0">1</a>
          </span>
          <span class="badge-group">
            <a href="./index.html?q=hue" class="badge badge-info">hue</a><a class="badge badge-info tag-modal-toggle"
              data-bs-toggle="modal" data-bs-target="#tag-example-list" data-title="hue" data-content="&lt;ul class=&quot;list-group&quot;&gt;
                  &lt;li&gt;&lt;a class=&quot;list-group-item list-group-item-action active&quot; href=&quot;./color-manipulation.html&quot;&gt;Color Manipulation&lt;/a&gt;
                  &lt;/ul&gt;" tabindex="0">1</a>
          </span>
          <span class="badge-group">
            <a href="./index.html?q=lightness" class="badge badge-info">lightness</a><a
              class="badge badge-info tag-modal-toggle" data-bs-toggle="modal" data-bs-target="#tag-example-list"
              data-title="lightness" data-content="&lt;ul class=&quot;list-group&quot;&gt;
                  &lt;li&gt;&lt;a class=&quot;list-group-item list-group-item-action active&quot; href=&quot;./color-manipulation.html&quot;&gt;Color Manipulation&lt;/a&gt;
                  &lt;/ul&gt;" tabindex="0">1</a>
          </span>
          <span class="badge-group">
            <a href="./index.html?q=chroma" class="badge badge-info">chroma</a><a
              class="badge badge-info tag-modal-toggle" data-bs-toggle="modal" data-bs-target="#tag-example-list"
              data-title="chroma" data-content="&lt;ul class=&quot;list-group&quot;&gt;
                  &lt;li&gt;&lt;a class=&quot;list-group-item list-group-item-action active&quot; href=&quot;./color-manipulation.html&quot;&gt;Color Manipulation&lt;/a&gt;
                  &lt;/ul&gt;" tabindex="0">1</a>
          </span>
        </p>
        <div class="modal modal-tag-example" id="tag-example-list" tabindex="-1" role="dialog"
          aria-labelledby="tag-example-title" aria-hidden="true">
          <div class="modal-dialog modal-dialog-scrollable" role="document">
            <div class="modal-content">
              <div class="modal-header">
                <h5 class="modal-title" id="tag-example-title"></h5>
                <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
              </div>
              <div class="modal-body">
                <div class="list-group"></div>
              </div>
            </div>
          </div>
        </div>
        <div id="map" class="map"></div>
        <table class="controls">
          <tr>
            <td><label for="hue">色调</label></td>
            <td><input id="hue" type="range" min="-180" max="180" value="0" /></td>
            <td><span id="hueOut"></span> °&nbsp;</td>
          </tr>
          <tr>
            <td><label for="chroma">饱和度</label></td>
            <td><input id="chroma" type="range" min="0" max="100" value="100" /></td>
            <td><span id="chromaOut"></span> %</td>
          </tr>
          <tr>
            <td><label for="lightness">亮度</label></td>
            <td><input id="lightness" type="range" min="0" max="100" value="100" /></td>
            <td><span id="lightnessOut"></span> %</td>
          </tr>
        </table>

      </div>
      <form method="POST" id="codepen-form" target="_blank" action="https://codesandbox.io/api/v1/sandboxes/define">
        <input id="codesandbox-params" type="hidden" name="parameters">
      </form>
    </div>

    <div class="row-fluid">
      <div class="span12">
        <p id="shortdesc">Demonstrates color manipulation with a raster source.</p>
        <div id="docs">
          <p>一个允许自由操作像素值的栅格资源对象。本示例中，对于传入瓦片资源，使用另一个栅格资源对象，在渲染之前进行逐像素调整 RGB 值。 此栅格操作，从 RGB 空间中获取像素值，转换为 HCL
            颜色空间，根据上边的色调、色度、亮度等控件的值进行调整， 最后将像素转回 RGB 空间并且进行渲染。
            PS：简单理解就是：RasterSource 这个对象，可以对于传入的栅格图层的瓦片进行像素级的颜色调整。比如可以把普通矢量图转为蓝黑色、墨绿色等。</p>
        </div>
      </div>
    </div>

    <div class="row-fluid">
      <h5 class="source-heading">main.js</h5>
      <pre><code id="example-js-source" class="language-js">import ImageLayer from &#x27;ol/layer/Image.js&#x27;;
import Map from &#x27;ol/Map.js&#x27;;
import View from &#x27;ol/View.js&#x27;;
import {Raster as RasterSource, StadiaMaps} from &#x27;ol/source.js&#x27;;

/**
 * Color manipulation functions below are adapted from
 * https://github.com/d3/d3-color.
 */
const Xn &#x3D; 0.95047;
const Yn &#x3D; 1;
const Zn &#x3D; 1.08883;
const t0 &#x3D; 4 / 29;
const t1 &#x3D; 6 / 29;
const t2 &#x3D; 3 * t1 * t1;
const t3 &#x3D; t1 * t1 * t1;
const twoPi &#x3D; 2 * Math.PI;

/**
 * Convert an RGB pixel into an HCL pixel.
 * @param {Array&lt;number&gt;} pixel A pixel in RGB space.
 * @return {Array&lt;number&gt;} A pixel in HCL space.
 */
function rgb2hcl(pixel) {
  const red &#x3D; rgb2xyz(pixel[0]);
  const green &#x3D; rgb2xyz(pixel[1]);
  const blue &#x3D; rgb2xyz(pixel[2]);

  const x &#x3D; xyz2lab(
    (0.4124564 * red + 0.3575761 * green + 0.1804375 * blue) / Xn
  );
  const y &#x3D; xyz2lab(
    (0.2126729 * red + 0.7151522 * green + 0.072175 * blue) / Yn
  );
  const z &#x3D; xyz2lab(
    (0.0193339 * red + 0.119192 * green + 0.9503041 * blue) / Zn
  );

  const l &#x3D; 116 * y - 16;
  const a &#x3D; 500 * (x - y);
  const b &#x3D; 200 * (y - z);

  const c &#x3D; Math.sqrt(a * a + b * b);
  let h &#x3D; Math.atan2(b, a);
  if (h &lt; 0) {
    h +&#x3D; twoPi;
  }

  pixel[0] &#x3D; h;
  pixel[1] &#x3D; c;
  pixel[2] &#x3D; l;

  return pixel;
}

/**
 * Convert an HCL pixel into an RGB pixel.
 * @param {Array&lt;number&gt;} pixel A pixel in HCL space.
 * @return {Array&lt;number&gt;} A pixel in RGB space.
 */
function hcl2rgb(pixel) {
  const h &#x3D; pixel[0];
  const c &#x3D; pixel[1];
  const l &#x3D; pixel[2];

  const a &#x3D; Math.cos(h) * c;
  const b &#x3D; Math.sin(h) * c;

  let y &#x3D; (l + 16) / 116;
  let x &#x3D; isNaN(a) ? y : y + a / 500;
  let z &#x3D; isNaN(b) ? y : y - b / 200;

  y &#x3D; Yn * lab2xyz(y);
  x &#x3D; Xn * lab2xyz(x);
  z &#x3D; Zn * lab2xyz(z);

  pixel[0] &#x3D; xyz2rgb(3.2404542 * x - 1.5371385 * y - 0.4985314 * z);
  pixel[1] &#x3D; xyz2rgb(-0.969266 * x + 1.8760108 * y + 0.041556 * z);
  pixel[2] &#x3D; xyz2rgb(0.0556434 * x - 0.2040259 * y + 1.0572252 * z);

  return pixel;
}

function xyz2lab(t) {
  return t &gt; t3 ? Math.pow(t, 1 / 3) : t / t2 + t0;
}

function lab2xyz(t) {
  return t &gt; t1 ? t * t * t : t2 * (t - t0);
}

function rgb2xyz(x) {
  return (x /&#x3D; 255) &lt;&#x3D; 0.04045 ? x / 12.92 : Math.pow((x + 0.055) / 1.055, 2.4);
}

function xyz2rgb(x) {
  return (
    255 * (x &lt;&#x3D; 0.0031308 ? 12.92 * x : 1.055 * Math.pow(x, 1 / 2.4) - 0.055)
  );
}

const raster &#x3D; new RasterSource({
  sources: [
    new StadiaMaps({
      layer: &#x27;stamen_watercolor&#x27;,
    }),
  ],
  operation: function (pixels, data) {
    const hcl &#x3D; rgb2hcl(pixels[0]);

    let h &#x3D; hcl[0] + (Math.PI * data.hue) / 180;
    if (h &lt; 0) {
      h +&#x3D; twoPi;
    } else if (h &gt; twoPi) {
      h -&#x3D; twoPi;
    }
    hcl[0] &#x3D; h;

    hcl[1] *&#x3D; data.chroma / 100;
    hcl[2] *&#x3D; data.lightness / 100;

    return hcl2rgb(hcl);
  },
  lib: {
    rgb2hcl: rgb2hcl,
    hcl2rgb: hcl2rgb,
    rgb2xyz: rgb2xyz,
    lab2xyz: lab2xyz,
    xyz2lab: xyz2lab,
    xyz2rgb: xyz2rgb,
    Xn: Xn,
    Yn: Yn,
    Zn: Zn,
    t0: t0,
    t1: t1,
    t2: t2,
    t3: t3,
    twoPi: twoPi,
  },
});

const controls &#x3D; {};

raster.on(&#x27;beforeoperations&#x27;, function (event) {
  const data &#x3D; event.data;
  for (const id in controls) {
    data[id] &#x3D; Number(controls[id].value);
  }
});

const map &#x3D; new Map({
  layers: [
    new ImageLayer({
      source: raster,
    }),
  ],
  target: &#x27;map&#x27;,
  view: new View({
    center: [0, 2500000],
    zoom: 2,
    maxZoom: 18,
  }),
});

const controlIds &#x3D; [&#x27;hue&#x27;, &#x27;chroma&#x27;, &#x27;lightness&#x27;];
controlIds.forEach(function (id) {
  const control &#x3D; document.getElementById(id);
  const output &#x3D; document.getElementById(id + &#x27;Out&#x27;);
  control.addEventListener(&#x27;input&#x27;, function () {
    output.innerText &#x3D; control.value;
    raster.changed();
  });
  output.innerText &#x3D; control.value;
  controls[id] &#x3D; control;
});
</code></pre>
    </div>

    <div class="row-fluid">
      <h5 class="source-heading">index.html</h5>
      <pre><code id="example-html-source" class="language-markup">&lt;!DOCTYPE html&gt;
&lt;html lang="en"&gt;
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;Color Manipulation&lt;/title&gt;
    &lt;link rel="stylesheet" href="node_modules/ol/ol.css"&gt;
    &lt;style&gt;
      .map {
        width: 100%;
        height: 400px;
      }
      table.controls td {
        padding: 2px 5px;
      }
      table.controls td:nth-child(3) {
        text-align: right;
        min-width: 4.5em;
      }
    &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div id&#x3D;&quot;map&quot; class&#x3D;&quot;map&quot;&gt;&lt;/div&gt;
    &lt;table class&#x3D;&quot;controls&quot;&gt;
      &lt;tr&gt;
        &lt;td&gt;&lt;label for&#x3D;&quot;hue&quot;&gt;hue&lt;/label&gt;&lt;/td&gt;
        &lt;td&gt;&lt;input id&#x3D;&quot;hue&quot; type&#x3D;&quot;range&quot; min&#x3D;&quot;-180&quot; max&#x3D;&quot;180&quot; value&#x3D;&quot;0&quot;/&gt;&lt;/td&gt;
        &lt;td&gt;&lt;span id&#x3D;&quot;hueOut&quot;&gt;&lt;/span&gt; °&amp;nbsp;&lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
        &lt;td&gt;&lt;label for&#x3D;&quot;chroma&quot;&gt;chroma&lt;/label&gt;&lt;/td&gt;
        &lt;td&gt;&lt;input id&#x3D;&quot;chroma&quot; type&#x3D;&quot;range&quot; min&#x3D;&quot;0&quot; max&#x3D;&quot;100&quot; value&#x3D;&quot;100&quot;/&gt;&lt;/td&gt;
        &lt;td&gt;&lt;span id&#x3D;&quot;chromaOut&quot;&gt;&lt;/span&gt; %&lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
        &lt;td&gt;&lt;label for&#x3D;&quot;lightness&quot;&gt;lightness&lt;/label&gt;&lt;/td&gt;
        &lt;td&gt;&lt;input id&#x3D;&quot;lightness&quot; type&#x3D;&quot;range&quot; min&#x3D;&quot;0&quot; max&#x3D;&quot;100&quot; value&#x3D;&quot;100&quot;/&gt;&lt;/td&gt;
        &lt;td&gt;&lt;span id&#x3D;&quot;lightnessOut&quot;&gt;&lt;/span&gt; %&lt;/td&gt;
      &lt;/tr&gt;
    &lt;/table&gt;

    &lt;script type="module" src="main.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;</code></pre>
    </div>

    <div class="row-fluid">
      <h5 class="source-heading">package.json</h5>
      <pre><code id="example-pkg-source" class="language-json">{
  &quot;name&quot;: &quot;color-manipulation&quot;,
  &quot;dependencies&quot;: {
    &quot;ol&quot;: &quot;8.2.0&quot;
  },
  &quot;devDependencies&quot;: {
    &quot;vite&quot;: &quot;^3.2.3&quot;
  },
  &quot;scripts&quot;: {
    &quot;start&quot;: &quot;vite&quot;,
    &quot;build&quot;: &quot;vite build&quot;
  }
}</code></pre>
    </div>
  </div>

  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.2.0/dist/js/bootstrap.bundle.min.js"></script>
  <script src="common.js"></script>
  <script src="color-manipulation.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.28.0/components/prism-core.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.28.0/plugins/autoloader/prism-autoloader.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.28.0/plugins/toolbar/prism-toolbar.min.js"></script>
  <script
    src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.28.0/plugins/copy-to-clipboard/prism-copy-to-clipboard.js"></script>
  <script src="./resources/common.js"></script>
  <script>
    document.getElementById('tag-example-list')
      .addEventListener('show.bs.modal', function (event) {
        const button = event.relatedTarget; // Button that triggered the modal
        this.querySelector('.modal-title').innerText = button.dataset.title;
        this.querySelector('.modal-body').innerHTML = button.dataset.content;
      });
  </script>
  <script>
    const releaseUrl = 'https://cdn.jsdelivr.net/npm/ol/package.json';
    fetch(releaseUrl).then(function (response) {
      return response.json();
    }).then(function (json) {
      const latestVersion = json.version;
      document.getElementById('latest-version').innerHTML = latestVersion;
      const url = window.location.href;
      const branchSearch = url.match(/\/([^\/]*)\/examples\//);
      const storageKey = 'ol-dismissed=-' + latestVersion;
      const dismissed = localStorage.getItem(storageKey) === 'true';
      if (branchSearch && !dismissed && /^v[0-9\.]*$/.test(branchSearch[1]) && '8.2.0' != latestVersion) {
        const link = url.replace(branchSearch[0], '/latest/examples/');
        fetch(link, { method: 'head' }).then(function (response) {
          const a = document.getElementById('latest-link');
          a.href = response.status == 200 ? link : '../../latest/examples/';
        });
        const latestCheck = document.getElementById('latest-check');
        latestCheck.style.display = '';
        document.getElementById('latest-dismiss').onclick = function () {
          latestCheck.style.display = 'none';
          localStorage.setItem(storageKey, 'true');
        }
      }
    });
  </script>
</body>

</html>